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Circulatory system -

The circulatory system is essentially responsible for spreading oxygen, nutrients, and hormones throughout your body. All of these ingredients of life are carried by blood via your blood vessels and are pumped by your heart.

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Circulatory system -

The heart is the most crucial part of the circulatory system, and arguably the entire body. It acts as a pump that pushes blood through your body’s vast network of arteries and veins. It truly is tireless, as it beats approximately 100,000 times a day.

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Circulatory system -

Arteries are basically the body’s highways, since they provide avenues that carry oxygen-rich blood away from the heart. Once the cells in your body consume the oxygen, your veins return the now oxygen-depleted blood back to the heart.

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Respiratory system -

Every time you breathe in and out, you are engaging your body’s respiratory system. The respiratory system is primarily responsible for bringing oxygen into the body when you inhale, and expelling carbon dioxide when you exhale. Without oxygen, the cells in our bodies would basically die.

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Respiratory system -

The major organs in the respiratory system are the lungs, although the trachea, bronchi, and diaphragm are also included. When you inhale, air enters through the nose or mouth, travels down the trachea, and enters the lungs via the bronchi, where oxygen is captured by tiny air sacs called alveoli.

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Respiratory system -

Your breathing is controlled by the diaphragm. During inhalation, the diaphragm contracts and moves downward, expanding the chest cavity and allowing air to flow into the lungs. During exhalation, the diaphragm relaxes, pushing air out.

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Digestive system -

Your body’s digestive system is responsible for breaking down food into nutrients, which your body uses for energy and growth. It also removes solid waste from the body, which happens when you feel the need to go to the toilet.

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Digestive system -

The first half of the digestive system is known as the digestive tract, which includes the mouth, esophagus, stomach, small intestine, and large intestine. Food is ingested in the mouth, where it is chewed and mixed with saliva, then travels down the esophagus to the stomach.

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Digestive system -

The second half of the system is made up of "accessory organs" like the liver, pancreas, and gallbladder. The liver processes nutrients, the pancreas breaks down sugar into energy, and the gallbladder stores bile that breaks down fats in the small intestine.

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Nervous system -

Your body’s nervous system is divided into two main parts: the central nervous system (CNS) and peripheral nervous system (PNS). The CNS, which consists of the brain and spinal cord, processes information and coordinates bodily functions, while the PNS connects the CNS to the rest of the body.

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Nervous system -

Your nervous system is made up of cells called neurons, which transmit messages all over your body that allow you to do things like breathing, talking, or eating. There are about 135 billion neurons in the human body, and they are connected via "synapses" so that they can communicate with each other.

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Nervous system -

The nervous system controls both voluntary actions (such as movement) and involuntary actions (like heartbeat and digestion). Your breathing is one of the only functions that can oscillate back and forth between voluntary and involuntary actions.

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Endocrine system -

The endocrine system is basically all about hormones. In order for your body to function properly, chemical hormones are released into your bloodstream so that your growth, metabolism, and mood can be regulated.

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Endocrine system -

Hormones come from minor organs known as endocrine glands, which include the pituitary gland and the thyroid (pictured). The pituitary gland controls other endocrine glands, while the thyroid regulates your metabolism.

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Endocrine system -

Each hormone in your body has a specific function. For example, insulin from the pancreas regulates blood sugar levels, while adrenaline from the adrenal glands (located on the kidneys) prepares the body for "fight or flight" responses. If your body experiences hormonal imbalances, it could lead to various health issues.

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Skeletal system -

The skeletal system is important in providing the body with its structural framework, as well as protecting the internal organs. It consists of bones, cartilage, ligaments, and joints, all of which work together to maintain your body’s shape and help you move.

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Skeletal system -

Despite what many people think, bones are actually living tissues that constantly change throughout life. The adult human skeleton has 206 bones, and they store minerals, produce blood cells in the bone marrow, and provide attachment points for muscles.

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Skeletal system -

Your body is able to move around because your bones meet at places called joints. They are classified by their range of motion, such as hinge joints like the knee and elbow, or ball-and-socket joints like the shoulder and hip.

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Muscular system -

The muscular system works hand-in-hand with the skeleton, and consists of three types of muscles: skeletal, smooth, and cardiac. Skeletal muscles, which are under voluntary control, attach to bones and facilitate movement. Smooth muscles, found in organs like the stomach and intestines, operate involuntarily. Cardiac muscle, found in the heart, also functions involuntarily.

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Muscular system -

Whenever you want to move your body, your nervous system sends a signal to your muscles, and the muscle fibers contract in response. This contraction pushes and pulls your skeletal system, thus creating movement.

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Muscular system -

Beyond movement, muscles also maintain your posture, stabilize your joints, and regulate your body’s temperature. Regular exercise can enhance the function of your muscles and prevent conditions such as muscle atrophy and weakness.

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Immune system -

The immune system is the body’s crucial protection against bacteria, viruses, and parasites. Without the immune system, your overall health would be significantly impacted and you would find yourself perpetually infected with diseases.

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Immune system -

Your immune system is primarily made up of white blood cells, antibodies, and various organs like the spleen and thymus. White blood cells are crucial in identifying and destroying foreign pathogens that enter the body.

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Immune system -

The immune system is constantly learning as it encounters new viruses and bacteria. Your body essentially has a memory that keeps a record of all the foreign bacteria and infections that it has encountered in the past, all so that it can defend your body in the future.

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Integumentary system -

Although this name is certainly strange, the integumentary system is something you’re actually very familiar with. It consists primarily of your skin, hair, and nails, and serves as a barrier that protects your body from external harm.

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Integumentary system -

The skin is the biggest part of the integumentary system. It regulates body temperature through sweating, and is also home to nerves that allow you to touch and feel the world around you.

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Integumentary system -

The skin has three main layers: the epidermis, dermis, and hypodermis. The epidermis is basically a waterproof barrier and it creates our skin tone. The dermis contains hair follicles and sweat glands. For its part, the hypodermis is made up of fat.

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Urinary system -

The urinary system is responsible for removing waste from your body through your urine. When your body produces excess substances that don’t have any nutrients leftover, it produces urine that is pushed out of the body via the bladder.

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Urinary system -

The kidneys are an essential part of the urinary system, as they filter blood, reabsorb important nutrients, and excrete excess waste as urine. They also regulate blood pressure and the creation of red blood cells.

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Urinary system -

After your kidneys filter your blood to create urine, the waste travels down your body’s ureters to the bladder, where it is stored until you go to the toilet.

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Reproductive system -

The reproductive system is the only system in the body that is drastically different depending on whether you are biologically male or female. It basically produces elements that facilitate the production of offspring, as well as hormones that define your sex.

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Reproductive system -

In females, the reproductive system consists mainly of the ovaries, uterus, and vagina. The ovaries are the most important, as they produce eggs and hormones like estrogen, while the uterus supports pregnancy.

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Reproductive system -

In males, the reproductive system includes the testes (which produce sperm and testosterone), the prostate, and the penis. Sperm production and transport are essential for the fertilization of the female egg.

Sources: (Verywell Health) (Britannica) (WebMD) (Medicine LibreTexts)

See also: Which countries have the highest organ donation rates?

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